JP2014239590A - Driving device for full-bridge circuit and power module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device for a full-bridge circuit having high reliability and a power module including the full-bridge circuit.SOLUTION: A driving device for a full-bridge circuit drives the full-bridge circuit according to a first mode that turns on a second power transistor and a fourth power transistor and passes a current through a path composed of the second power transistor and the fourth power transistor; a third mode that turns on the fourth power transistor and passes a current through a path composed of a first power transistor, the fourth power transistor, and a load; and a fourth mode that turns on the second power transistor and passes a current through a path composed of the second power transistor, a third power transistor, and the load.

Description

The present invention relates to a driving device for driving a full bridge circuit and a power module including the full bridge circuit.

The full bridge circuit is also called an H bridge circuit because four power transistors are connected in an H shape, and is used in a power conversion device or a motor drive device. For example, Toshiba TB6562ANG / AFG is one of the motor drive devices currently on the market, and is a power module in which two sets of full bridge circuits and their control circuits are sealed in a single resin sealing body. . Patent Document 1 describes a technique related to constant current driving in such a motor driving device.

FIG. 6 is an operation explanatory diagram of the full bridge circuit described in Patent Document 1, and arrows indicate the flow of current in each period. The first to fourth power transistors M1, M2, M3, and M4 are connected in an H shape, and the connection point between the first and second power transistors M1 and M2 and the connection between the third and fourth power transistors M3 and M4. The first coil L1 is connected between the points. First, as shown in FIG. 6A, the second and fourth power transistors M2 and M4 are turned on, and a current flows through a path including M2, M4, and L1 (first mode). Next, as shown in FIG. 6B, the second and fourth power transistors M2 and M4 are turned off, and a current flows through a path including M1, M3, and L1 (second mode). Next, as shown in FIG. 6C, the fourth power transistor M4 is turned on again, and a current flows through a path formed by M1, M4, and L1 (third mode). The conventional full bridge circuit can control the current flowing through the coil L1 to be substantially constant by repeating the above operation.

JP 2002-204150 A

By the way, since the drive device of a full bridge circuit and the power module including a full bridge circuit have a complicated structure with many parts, it is required to improve the reliability.

The present invention provides a driving device and a power module for a full bridge circuit having high reliability.

According to one aspect of the present invention, there is provided a full-bridge circuit driving apparatus for driving a full-bridge circuit including a first power transistor, a second power transistor, a third power transistor, and a fourth power transistor. A first mode in which the second power transistor and the fourth power transistor are turned on to pass a current through a path formed by the second power transistor, the fourth power transistor, and the load; A third mode in which the fourth power transistor is turned on to pass a current through a path including the first power transistor, the fourth power transistor, and the load; and the second transistor is turned on and the second transistor is turned on. A fourth mode in which current flows through a path consisting of the power transistor, the third power transistor and the load. And drives the full-bridge circuit and de accordance.

ADVANTAGE OF THE INVENTION According to this invention, the drive device and power module of a full bridge circuit which have high reliability can be provided.

It is a circuit diagram showing composition of a power module which has a full bridge circuit concerning a 1st embodiment of the present invention. It is a block diagram which shows the structure of the power module which has a full bridge circuit which concerns on the 1st Embodiment of this invention. It is operation | movement explanatory drawing of the power module which has a full bridge circuit which concerns on the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the drive device of the full bridge circuit which concerns on the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the drive device of the full bridge circuit which concerns on the 2nd Embodiment of this invention. 6 is an operation explanatory diagram of a full bridge circuit described in Patent Document 1. FIG.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic. Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention have the following structure and arrangement of components. It is not something specific. The embodiment of the present invention can be variously modified within the scope of the claims.

(First embodiment)
1 and 2 are configuration diagrams showing the configuration of a power module having a full bridge circuit according to the first embodiment of the present invention. The power module 100 having the full bridge circuit according to the present embodiment includes a first full bridge including a first power transistor M1, a second power transistor M2, a third power transistor M3, and a fourth power transistor M4. A second full bridge circuit 20 comprising a circuit 10, a fifth power transistor M5, a sixth power transistor M6, a seventh power transistor M7, and an eighth power transistor M8, and first and second full transistors. And a driving device MIC for driving the bridge circuits 10 and 20. The power module 100 includes at least one set of full bridge circuits of the first and second full bridge circuits 10 and 20.

Each of the first to eighth power transistors M1, M2, M3, M4, M5, M6, M7, and M8 has a drain terminal (high-voltage side terminal), a source terminal (low-voltage side terminal), and a gate terminal (control terminal). And a power MOSFET having a parasitic diode capable of flowing a current from each source terminal toward the drain terminal.

In the first full bridge circuit 10, the drain terminals of the second and third power transistors M2 and M3 are connected to a motor power supply. The source terminal of the second power transistor M2 is connected to the drain terminal of the first power transistor M1, and the source terminal of the third power transistor M3 is connected to the drain terminal of the fourth power transistor M4. The source terminals of the first and fourth power transistors M1 and M4 are grounded via the first detection resistor Rs1. A connection point between the first and second power transistors M1 and M2 is a first output terminal of the power module 100, and is connected to one end of the first coil L1 as a load. A connection point between the third and fourth power transistors M3 and M4 is a second output terminal of the power module 100 and is connected to the other end of the first coil L1 which is a load. That is, the first to fourth power transistors M 1, M 2, M 3, and M 4 are connected in an H shape to constitute the first full bridge circuit 10.

In the second full bridge circuit 20, the drain terminals of the sixth and seventh power transistors M6 and M7 are connected to the motor power supply. The source terminal of the sixth power transistor M6 is connected to the drain terminal of the fifth power transistor M5, and the source terminal of the seventh power transistor M7 is connected to the drain terminal of the eighth power transistor M8. The source terminals of the fifth and eighth power transistors M5 and M8 are grounded via the second detection resistor Rs2. A connection point between the fifth and sixth power transistors M5 and M6 is a third output terminal of the power module 100, and is connected to one end of the second coil L2 as a load. A connection point of the seventh and eighth power transistors M7 and M8 is a fourth output terminal of the power module 100, and is connected to the other end of the second coil L2 that is a load. That is, the fifth to eighth power transistors M 5, M 6, M 7, and M 8 are connected in an H shape to constitute the second full bridge circuit 20.

The driving device MIC flows through at least the gate terminals of the first to eighth power transistors M1, M2, M3, M4, M5, M6, M7, and M8 and the first and second full bridge circuits 10 and 20. The first and second detection resistors Rs1 and Rs2 for detecting current are connected. The driving device MIC is also connected to the first to fourth output terminals of the power module 100, and turns on and off each power transistor in order to control the current flowing through each full bridge circuit to a predetermined value.

The power module 100 according to this embodiment includes first to eighth power transistors M1, M2, M3, M4, M5, M6, M7, and M8, a driving device MIC, a plurality of inner leads IL, and a plurality of outer layers. A lead OL and a resin package MR are provided. Each power transistor, the driving device MIC, and the plurality of inner leads IL are sealed by the resin package MR and led out of the resin package MR through the plurality of outer leads OL.

Each power transistor and the driving device MIC are mounted on a plurality of inner leads IL and are connected to each other by a metal wire (not shown). The first power transistor M1 is placed on the first inner lead, the second and third power transistors M2 and M3 are placed on the second inner lead, and the fourth power transistor M4 is the third power lead. Is placed on the inner lead. The fifth power transistor M5 is placed on the fourth inner lead, the sixth and seventh power transistors M6, M7 are placed on the fifth inner lead, and the eighth power transistor M8 is the sixth power lead. Is placed on the inner lead. Further, the driving device MIC is placed on the seventh inner lead. The first and fourth inner leads are led out from the first side surface (the upper side surface in FIG. 2) of the resin package MR, and the third and sixth inner leads are the second side surface (the lower side in FIG. 2). The second, fifth, and seventh inner leads are derived from the first and second side surfaces of the resin package MR.

FIG. 3 is an operation explanatory diagram of the power module having the full bridge circuit according to the first embodiment of the present invention, and arrows in the figure indicate paths through which current flows. FIG. 4 is a flowchart showing the operation of the full bridge circuit driving apparatus according to the first embodiment of the present invention. Since the basic operation of the first full bridge circuit 10 is the same as that of the second full bridge circuit 20, only the first full bridge circuit 10 will be described here. The drive device MIC according to the present embodiment drives the first and second full bridge circuits 10 and 20 according to at least the first to fourth modes (operation states).

First, as shown in FIG. 3A, the driving device MIC drives the first full bridge circuit 10 according to the first mode. The second and fourth power transistors M2 and M4 are turned on, the first and third power transistors M1 and M3 are turned off, and a current flows through a path made up of M2, M4 and L1. In the first mode, the current flowing through the first coil L1 increases with time.

Next, as shown in FIG. 3B, the driving device MIC drives the first full bridge circuit 10 in accordance with the second mode (regeneration mode). At least the second and fourth power transistors M2 and M4 are turned off, and a current flows through a path composed of M1, M3, and L1. When the first and third power transistors M1, M3 are turned off, the current flows through the parasitic diodes of the first and third power transistors M1, M3, and the first and third power transistors M1, M3 are turned on. Then, the current flows through the channels of the first and third power transistors M1 and M3. In the second mode, the current flowing through the first coil L1 decreases with time.

Next, as shown in FIG. 3C, the driving device MIC drives the first full bridge circuit 10 according to the third mode (low-side attenuation mode). The fourth power transistor M4 is turned on, at least the second and third power transistors M2 and M3 are turned off, and a current flows through a path composed of M1, M4, and L1. When the first power transistor M1 is turned off, the current flows through the parasitic diode of the first power transistor M1, and when the first power transistor M1 is turned on, the current flows through the channel of the first power transistor M1. Flowing. In the third mode, the current flowing through the first coil L1 gradually decreases as time passes as compared to the second mode. The driving device MIC may drive the first full bridge circuit 10 in accordance with the third mode without passing through the second mode after the first mode, and the second mode after the third mode. Accordingly, the first full bridge circuit 10 may be driven.

Next, after driving according to the first mode and the second mode again, as shown in FIG. 3D, the driving device MIC performs the first full-bridge circuit 10 according to the fourth mode (high-side attenuation mode). Drive. The second power transistor M2 is turned on, at least the first and fourth power transistors M1 and M4 are turned off, and a current flows through a path formed by M2, M3, and L1. When the third power transistor M3 is turned off, the current flows through the parasitic diode of the third power transistor M3, and when the third power transistor M3 is turned on, the current flows through the channel of the third power transistor M3. Flowing. In the fourth mode, the current flowing through the first coil L1 gradually decreases as time passes, compared to the second mode. The driving device MIC may drive the first full-bridge circuit 10 according to the fourth mode without passing through the second mode after the first mode, and the second mode is followed by the fourth mode. Accordingly, the first full bridge circuit 10 may be driven.

The drive device MIC according to the present embodiment repeatedly switches between the first to fourth modes as described above to drive the first full bridge circuit 10, thereby changing the current flowing through the first coil L1 to a predetermined value. Can be controlled.

In addition, the driving device MIC according to the present embodiment reduces the time bias in which the current flows through each power transistor by alternately performing the attenuation according to the third mode and the attenuation according to the fourth mode as described above. can do. Therefore, the drive device MIC according to the present embodiment can suppress the generation of heat and destruction of the power transistor due to the bias of the energization time, and can provide a full-bridge circuit drive device and power module with high reliability.

In particular, when the drive time according to the attenuation mode (third and fourth modes) is long as in the case of constant current control of the motor, the energization time of a specific power transistor becomes long. The effect of the device MIC is great.

In addition, the inner leads on which the first and fourth power transistors M1 and M4 through which current flows in the third mode are respectively derived from different side surfaces of the resin package MR, and the current through which current flows in the fourth mode. Inner leads on which the second and third power transistors M2 and M3 are placed are respectively derived from different side surfaces of the resin package MR. Therefore, the power module 100 according to the present embodiment can efficiently dissipate the heat generated by the power transistor, and can provide a full-bridge circuit driving device and power module having high reliability.

(Second Embodiment)
FIG. 5 is a flowchart showing the operation of the full bridge circuit driving apparatus according to the second embodiment of the present invention. The drive device MIC according to the present embodiment compares the temperatures of the first and fourth power transistors M1 and M4 with the temperatures of the second and third power transistors M2 and M3, and compares the temperatures of the third and third power transistors M2 and M3 according to the comparison result. The attenuation according to the mode and the attenuation according to the fourth mode are selectively performed. Specifically, after the first full bridge circuit 10 is driven according to the first mode, the driving device MIC compares the temperature of each power transistor or the temperature of the inner lead IL on which each power transistor is mounted, The operation mode is selected so that the temperature distribution in the power module 100 is uniform. Note that the first full bridge circuit 10 may be driven according to the second mode before or after the third mode and the fourth mode.

The drive device MIC according to the present embodiment selectively performs the attenuation according to the third mode and the attenuation according to the fourth mode so as to suppress the temperature variation in the power module 100, thereby generating the heat generated by the power transistor. It is possible to provide a driving device and a power module for a full bridge circuit that can suppress the occurrence of breakdown and have high reliability.

As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. That is, it goes without saying that the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description. For example, the power transistor may be a discrete element composed of a P-channel MOSFET, IGBT, or bipolar transistor, or may be a transistor element formed on the same chip as the driving device. The first to fourth modes are modes in which a current in the same direction flows through the first coil L1, but the driving device drives the full bridge circuit according to another mode in which a current in the opposite direction flows. Also good.

10 first full bridge circuit 20 second full bridge circuit 100 power module M1 first power transistor M2 second power transistor M3 third power transistor M4 fourth power transistor M5 fifth power transistor M6 sixth Power transistor M7 seventh power transistor M8 eighth power transistor MIC driving device L1 first coil L2 second coil Rs1 first detection resistor Rs2 second detection resistor

Claims (5)

A driving device for a full bridge circuit for driving a full bridge circuit comprising a first power transistor, a second power transistor, a third power transistor, and a fourth power transistor,
A first mode in which the second power transistor and the fourth power transistor are turned on to pass a current through a path formed by the second power transistor, the fourth power transistor, and the load;
A third mode in which the fourth power transistor is turned on to pass a current through a path including the first power transistor, the fourth power transistor, and the load;
The full-bridge circuit is driven in accordance with a fourth mode in which the second transistor is turned on and a current is passed through a path including the second power transistor, the third power transistor, and the load. A full bridge circuit drive. The full-bridge circuit driving apparatus according to claim 1, wherein the third mode and the fourth mode are switched based on a predetermined condition. 3. The full-bridge circuit driving device according to claim 1, further comprising a second mode in which a current flows through a path including the first power transistor, the third power transistor, and the load. 4. . The full-bridge circuit driving apparatus according to any one of claims 1 to 3, wherein the load is a motor coil. A full-bridge circuit comprising a first power transistor, a second power transistor, a third power transistor, and a fourth power transistor, and a full-bridge circuit driving device according to claim 1. A power module characterized by that.

Images